New Techniques, Cameras Improve Colonoscopy

Oct. 27, 2009 (San Diego) -- The screening test no one likes to talk about, colonoscopy, is getting more accurate, thanks to better techniques and equipment, such as a camera that helps detect polyps and other lesions lurking behind the folds of the intestines.

That was the message at a news briefing at the annual meeting of the American College of Gastroenterology in San Diego.

A routine colonoscopy, a visual inspection of the colon using a special flexible scope, is generally recommended at age 50 to detect cancer and precancerous growths, and earlier if there is a family history or for certain ethnic groups.

But the test isn't foolproof, and researchers have been trying to improve the technology.

A 'Third Eye' for the Colon

One improvement in colonoscopy is a disposable device that is passed through the instrument channel of a standard colonoscope, called the Third Eye Retroscope (TER), which gives physicians a better look at the lesions they may miss with standard screening equipment.

''The third eye is a camera on the end of a probe,'' says researcher Daniel C. DeMarco, MD, medical director of endoscopy at the Baylor University Medical Center, Dallas. It allows physicians to inspect the colon backward as they withdraw the scope.

''The image is not quite as clear [as the forward image],'' he says. Still, the idea is to help physicians detect the lesions -- polyps and adenomas -- behind the many folds and turns in an intestine, which has remained difficult despite other advances in equipment.

At the meeting, DeMarco presented the results of his study, in which nearly 300 patients underwent colonoscopies using the third eye camera. By using a split screen monitor, DeMarco's team was able to detect which growths were observed due to the camera that wouldn't have been detected with traditional colonoscopy alone. The overall increased detection rate for all adenomas using the third eye device was 16%, with an even greater detection rate for larger growths than smaller ones.

Is High-Definition Better?

High-definition colonoscopy may detect more lesions than standard ''white light'' colonoscopy, according to researcher Kenneth R. DeVault, MD, a gastroenterologist at the Mayo Clinic in Jacksonville, Fla.

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As the high-definition equipment was being phased in, DeVault's team assigned 1,200 patients to standard exams and another 1,200 to high-definition exams, then compared the detection rate of adenomas.

''Overall we found adenomas in about 30% who had high-definition and in 24% of those who had standard-definition colonoscopy," he says.

But most were small, he says. High-definition is not available everywhere, he says, although the newer machines are now high-definition. So in time, the technology will be widespread.

Tackling the Flat Lesion Problem

In other research, Charles Kahi, MD, assistant professor of clinical medicine at Indiana University in Indianapolis, compared high-definition white light colonoscopy in 339 patients with ''chromocolonoscopy,'' in which a dye is sprayed to help improve detection of lesions, in 321 patients.

Overall, the results of the dye technique were disappointing, he says. The differences in lesion detection were small. There was no increase in overall adenoma detection and there was a modest increase in flat and small adenoma detection.

The results, he says, don't support chromocolonoscopy for average-risk patients.

Message to Patients

Although the newer technologies are not yet widespread, DuVault said it would make sense for patients scheduling a colonoscopy to at least ask their doctor about the availability of high-definition colonoscopies.

Despite the bells and whistles, preparation of the colon by the patient before the test is still one of the key factors contributing to the accuracy of the test, doctors stressed. Other factors that have been shown to improve results include the experience of the physician performing the test.

DeMarco says colonoscopy's effectiveness rate is good but that the new technology will improve detection more. "We are trying to make something that's [already] very good better."